The recent proposal to remove the "safe" status formerly granted to partially hydrogenated vegetable oils in the United States has been reported as an impending "ban" on trans-fats. This is certainly a welcome move by the U.S. Food and Drug Administration (FDA) that would probably result in the bulk of the trans-fats currently in the food supply being removed.
However amidst all of the praise for this regulatory proposal, there are many questions not being asked about its limitations and silences. Industrial trans-fats themselves are in fact not being "banned," and nor are there any limits to be placed on the trans-fats content of foods. Nor are other minor sources of trans-fats being banned or regulated. At the same time few questions are being asked as to the safety and health implications of the processing techniques and ingredients that will replace trans-fats and partially hydrogenated vegetable.
Prior to this announcement, the FDA had placed no restriction on trans-fat content in foods. It had only required labeling of trans-fat content over 0.5 grams per serve. Anything under 0.5 that could be labelled "0 grams trans-fats", which could be quite misleading. Yet countries such as Denmark have since 2004 imposed a 2% limit of trans-fats in foods, and even New York City had a 0.5 grams per serving, which has also mistakenly been referred to as a "ban."
The FDA's proposal to remove the "generally recognized as safe" status of partially hydrogenated vegetable oils -- the primary source of trans-fats in the food supply -- is significant. Yet having finally acknowledged that industrial trans-fats are a health hazard, and that there is no recognized "safe" level of consumption of trans-fats, the FDA is not in fact placing any bans or limits on trans-fats levels in foods per se. The FDA also acknowledges that there are two other sources of industrial trans-fats that it does not intend to regulate or ban.
One such source of industrial trans-fats is the initial process of extracting and refining vegetable oils using extremely high temperatures, such as during the deodorization process. This may produce trans-fats of the order of 1 to 4%. While these quantities may be relatively low compared with those produced by the partial hydrogenation process, there are enormous quantities of these unhydrogenated vegetable oils now flowing through the food supply and through our bodies. It's possible that the continual reheating of deep-frying frying oils at very high temperatures over a long period of time also produces small amounts of trans-fats.
Vegetable oil producers certainly wouldn't want the public to know that there may be trans-fats in their oils, nor to have any restrictions placed on their processing methods or use. Similarly those nutrition experts and public health organizations that promote vegetable oils high in polyunsaturated fats would find it difficult to present these unhydrogenabted oils as "healthy oils" if the presence of trans-fats was more widely known. It is therefore no surprise that we see little discussion or analysis of this source of trans-fats.
Another source of industrial trans-fats is the technique of fully hydrogenating vegetable oils, which is used to transform all of the unsaturated fats into saturated fats. Yet this process of chemically transforming fats is usually incomplete, resulting in low levels of trans-fats in the end product of up to 2%. So it's interesting that the same technique that chemically transforms fats into trans-fats will continue to be permitted for use, as long as the process is continued to the point where low-levels of trans-fats are formed. But are even fully hydrogenated oils safe? Have their health effects been studied separately to partially hydrogenated oils?
Importantly, few nutrition experts or government regulators are questioning what partially hydrogenated vegetable oils will be substituted with. Their main worry has been that trans-fats aren't replaced with saturated fats. But food companies are now using a range of old and new food processing techniques, additives, and vegetable oil varieties that achieve the same functionality as trans-fats, such as a long shelf life, processing stability, mouth-feel, and the crunch they impart on foods. Blending fully hydrogenated and unhydrogenated vegetable oils is one such strategy being used to produce a low-trans-fat product.
Another technique increasingly being used to chemically reconstitute fats is the process of interesterification. Since the 1990s many margarine producers have been subjecting vegetable oils to a combination of full hydrogenation, fractionation and interesterification techniques in order to produce a low-trans-fat product. Few studies have examined the health effects of consuming interesterified fats, or what I call i-fats, but some of these studies have suggested possible harmful effects. We thereby risk repeating the trans-fats fiasco by allowing and encouraging the use of novel and inadequately tested fats.
While the FDA's proposed ban of partially hydrogenated oils is an important step forward, there is more that it -- and other countries -- could do to regulate trans-fats and other potentially hazardous fats and oils. It could ban all oil processing techniques that produce industrial trans-fats. It could ban or set very low limits on the presence of industrial trans-fats in food products. And it could remove the "generally recognized as safe" status of other processing techniques that chemically reconstitute fats, until such time as they have been proven safe and healthful.